Salmonella is similar to E. coli in the aspects of morphology or physiology but is categorized in an independent genus for the convenience in clinical use by the proposal of K. Kauffmann et al. Salmonella has been isolated from enteritis and gastroenteritis patients and from animals with diverse diseases since Salmonella choleraesuis was first isolated from a pig died of hog cholera by Salmon and Smith in 1885. Salmonella has also been isolated from health animals such as chicken, cow, pig, goat, dog, and cat and from our environment.
More than 2,000 serotypes of Salmonella have been reported so far and it can be largely divided into two groups, one of which is the group that has host specificity and the other of which is the group that does not have host specificity. Salmonella is a genus of rod-shaped, Gram-negative and non-spore-forming It is a parasite living in a variety of animals.
Salmonella infectious disease is developed in different forms. Enteritis is the most general form of Salmonella infection. Once infected with Salmonella, such symptoms as rough skin, anorexia, conjunctivitis, depression, pale feces, spleen enlargement, and even death are observed.
Various drugs have been used for the treatment of Salmonella infection. However, those drugs known so far cannot lead complete cure. So, it is more important to prevent the infection than to treat it.
Damage in livestock industry caused by Salmonella infection is rather huge. Therefore, it is an urgent request to develop a method for prevention and effective treatment of Salmonella infection.
The utilization of bacteriophage is now highly drawing our attention as an effective way of treating bacterial disease. In particular, our interests in bacteriophage grow with the preference of nature-friendly method. Bacteriophage is an extremely small microorganism infecting bacteria, which is generally called phage in short. Bacteriophage is an obligate intracellular parasite that multiplis inside bacteria by making use of some or all of the host biosynthetic machinery. Upon completion of the multiplication, offspring bacteriophages are coming out of the host cell with destroying the host bacteria. The infection of bacteriophage in bacteria is very unique and specific, so only specific bacteria can be infected with a specific bacteriophage. That is, there is a limitation in bacteria that can be infected with bacteriophage. Thus, bacteriophage can only kill specific target bacteria without effecting on any other bacteria.
Bacteriophage was first found in 1915 when English bacteriologist Twort was studying on the phenomenon that micrococcus colony was being melted clearly by some reasons. And also, French bacteriologist d'Herelle noticed that Shigella disentriae was melted by something in filtrate of dysentery patient's feces and afterwards he separated bacteriophage independently by the following study and named it bacteriophage which meant ‘eating bacteria’. Since then, bacteriophages corresponding to different pathogenic bacteria including Shigella, Salmonella and Vibrio cholerae have been continuously reported.
Owing to its capability of killing bacteria, bacteriophage has been in the center of our interest to fight with bacterial infection and studies followed thereon. However, since Flemming found out penicillin, antibiotics have been supplied and the study on bacteriophage has been limited in some east European countries and old Soviet Union. It was not until 2000 that the conventional antibiotics demonstrated their problems in use because of increasing antibiotic-resistant bacteria. So, once again, bacteriophage draws out attention as an alternative anti-bacterial agent that can take the place of the conventional antibiotics.
Therefore, the present inventors tried to develop a composition for prevention or treatment of Salmonella infection by using bacteriophage that can destroy Salmonella selectively and further tried to establish a method for prevention and treatment of Salmonella infection using the same. At last, the inventors isolated a proper bacteriophage from the nature and secured the gene sequence of its genome for the distinguishment from other bacteriophages. Then, the present inventors succeeded in developing a composition comprising the said bacteriophage as an active ingredient and further completed this invention by confirming that the said composition of the invention can be effectively used for prevention and treatment of Salmonella infection.